Carburetor



G. MEMlNl CARBURETOR June 27, 1933.

Filed June 25, 1931 Patented June 27, 1933 UNITED STATES GIACOMO MEMIN'I, 0F MILAN, ITALY CABIBUBETOR Application med June 23, 1981, Serial No. 546,286, and in Italy-Tune 28, 1980.

It is known that variations of speed of aninternal combustion engine cause variations in the suction of the carburetor. Since the,

suction acts differently on the air and on the petrol, on account of their different densities a simple carburetor discharging a jet o petrol from' a reducing or spraying nozzle placed in the center of Lhe column or stream of air, would give an exactly proportioned mixture only when operating at a predetermined speed, but would impoverish the mixture with v a decrease and would too much enrich it with an increase in the openingof the control valve.

All modern carburetors have one or another means tending to maintain the mixture uniform or correct whatever may be the state of control of the engine. The present invention consists of a new device by which this aim is attained more satisfactorily than formerly by other methods.

The present device is distinguished from others' in several respects including the fact that the fuel flows, through at least one calibrated port or nozzle, from the constant level vessel into a vaporization chamber which communicates, at the upper end, with the discharge opening into the low pressure or most constricted part of the mixer, the aforesaid chamber also communicating with the atmosphere through at least one calibrated channel, and also communicating with at least one suitably placed opening or passage in the body of the mixer where the suction is less than it is at the low pressure point, this last communication being through a passage by` which the air current, entering the aforesaid chamber from the mixer, cannot reverse its direction, so that from the combined actions of these connections, the suction in the fuel chamber will automatically vary-with variations in the opening of the throttle-at a rate diifering from that at the middle or constricted point of the mixer, thus obtaining an issue of fuel from the discharge in the most suitable roportions for the various loads.

Two orms of the device according to the invention are shown by way of example only, in the attached rawing.

Fi 1 is a longitudinal vertical section of 56 a car uretor provided with a device accord- 1n to the invention.

igs. 2 and 3 show in longitudinal vertical section another embodiment, Fi 2 showing the condition when working at ow or minimum speed and Fig. 3 the condition during a eriod of increase of engine speed.

eferrin to Fig. 1, changes of engine speed are o tained as usual by -opening more or less the butterfly throttle 1. The mixing pipe or conduit 13 may be as usual, with a venturi section or throat piece 13, the center of which is a zone of maxlmum suction, below the throttle.

The petrol (or other liquid fuel) flows, by

tube 2, to constant level vessel 3 lin which the level 4 of the fuel is kept practically constant by means of any suitable level control device or float 5. u y

Through the large passage or port 6 and 75 then the small calibrated aperture or orifice 7 (which I'will call the principal or cortrolling orifice or nozzle) the petrol penetrates into the fuel vaporization chamber 8 reaching, when the motor is stopped the same level as in the constant-level vessel 3. Y

Three passa es or channels 9, 10 and 20, connect with t e vapor space of chamber 8;

'the first channel 9 beingl large and free, ex-

tending through tube 12 delivering at 11 into 85 the central zone of the mixer 13 (that is, into the zone of greatest suction) with one or more holes oriented and disposed 4so as to utilize to the lutmost this suction, as, for example,- the upturned or inclined mouth or discharge exit 11 facing in the same direction as the air current; the second channel 10 leading through sundry fine calibrated holes-14 into the chamber 8 and bein sup liedwith air by passage 15 in the wa l of t e mixer near 95 tube 12 and' preferably below or ahead of it; the third channel 20 leading from the atmosphere and through sundry small calibrated holes 21l opening into the chamber 8.

The normal level 4 of the petrol stands 100 slightly below that of exit 11 and passage so that the petrol may not escape through these when the engine is idle. The calibrated orifice 7 however is situated somewhat below this level.

With an increase in the opening of throttle 1 and with an increase in the load on the engine the suction and air travelincrcase, and thereby the current of air entering the passage 15 diminishes until it is reduced, at the maximum load to a very small rate, without, however, being entirely suppressed or rc- Versed. Under these conditions the force under which the petrol lows through the nozzle 7, is the result of 'the difference of altitude or head between the constant level in vessel 3 and the nozzle 7 affected by the low pressure, relative to that of the surrounding air, which exists in chamber 8.

Now, if the passage 15 and connecting channel or passage 10 did not exist and the air entered chamber 8 only by channel 20, the low pressure in chamber 8 would vary almost proportionately to the low pressure produced by the suction ofthe carburetor at the discharge opening 11 whilst the difference between the level at 4 and at the nozzle 7 would remain constant. Hence, if such nozzle and passages are adjusted so that the' proportions of the mixture are right for an average load, then, at maximum load the mixture will bc too poor in fuel.

If, however, the air entering chamber 8 is divided between channel and channel 10, these can be so adjusted that, whilst the quantity of air entering chamber 8 through channel 20 increases under an increase of load and therefore of suction, the -current of air' entering through channel 10 automatically decreases, without however being entirely suPPressed or reversed.

In such a case the lowering of pressure in chamber 8 will vary at a different rate from that of the suction at the discharge 11 namely at a greater rate than that variation, vso that automatically there is provided a correct proportion of thev mixture either at average load or at maximum load on the motor.

At slow speeds the suction effect being less,

the level of the petrol in chamber 8 rises until nearly at the same height as in vessel 3; if, at this time, the throttle 1 is opened suddenly, the petrol accumulated in chamber 8 is quickly drawn in by the suction inthe mixer, which, for a moment, becomes still weaker so that it is unable to canse petrol to issue from nozzle 7 in suilicient quantity to form a mixture which would allow the engine to recover speed.

When throttled down for running idle, the throttle being nearly closed, there hardly sufficient suction in the mixer foi the carburetor to function, and for that reason the motor is generally made to draw in the necessary petrol by a separate channel 16 opening at 17 in front of the throttle 1, that is, at a point where a strong suction exists on account of the narrowing of the passage, and said channel 16 connecting through a calibrated hole with some point where there is a supply of petrol. In the case of the present invention, the channel 16 connects either with passage 18 at the bottom of chamber 8 or with passage 19 in the extension 6l of this chamber below nozzle 7, or with both of these `points simultaneously, according to how it may be desired to vary the effect of channel 16 on the rapidity of emptying chamber 8 at the time of recovering speed.

In the variation shown in Figs. 2 and 3, the chamber 8 is prolonged at its upper end by a cowl or extension 22 which has a line hole or port 23 at the top. The principal nozzle 7 is, in this case, arranged to deliver into an inner compartment, produced by a wall or tube 24 which is shown as narrowed at 25 and which opens freely near cowl 22. At the base\ tube 24 has large holes 26 communicating with chamber 8. The inlet 25 to compartment 24 is in alinement with the atmosphere port 23.

The operation of the invention may be described as follows. Whilst running at slowest speeds, there is practically no suction in chamber 8 because there is hardly any Suction in the mixer; the petrol, therefore, risesto the same level as in vessel 3 (Fig. 1). At the moment of opening up the throttle, the petrol which .is in chamber 8 and channels 10 and 20 is quickly vaporized and sucked along tube 9; but, on account of its own inertia, it might be sucked in too late resulting in a mixture too poor in the first instance and .too rich later as the inertia decreases or changes sign; the' acceleration will, therefore, not be gradual. It is here that the device of the present invention intervenes with its regulating action,by the functioning of the air passage 10 as already indicated.

Referring to Fig. 3 the arrows indicate the explanation of the action. Part lof the air coming through the fine hole 23 flows strongly into tube 25 and, pressing on the petrol contained in tube 24 helps it to issue through holes 26 into chamber 8 from whence its vapor is sucked along channel 9 whilst the jet has hardly commenced to function; land a part of the air entering at 23 goes directly to channel 9 passing around tube 25. As the engine increases its speed, the suction in the mixer increases and jet 7 functions more and more energetically; the air entering through hole 23 passes more easily outside tube 25 than inside where it is obstructed by the petrol issuing from 7 and where it no longer finds a surface of petrol on which to press; and normal running conditions prevall.

In practise the particular methods of carrying out the invention may, naturally, be

varied Without, however, departing from the essence of the present invention.

vHaving now particularly described and ascertained the nature of my said invention and in what manner the same is to be per- Y ing conduit and having its discharge near the zone of maximum suction thereof, and a supplemental air passage-leading from an inlet in the mixing conduit at a zone where the suction is less than at said vapor discharge and arranged to divert part of the air flowing into the conduit and conduct itinto the vaporization chamber to control the suction therein; the chamber having within it a wall enclosing an inner compartment into which the fuel nozzle directly delivers, and the chamber having an upper extension with an air port leading into it, and the inner compartment having an upper extension with an air inlet in alinement with said air port.

2. A carburetor for an engine comprising in combination with a mixing conduit, a chamber receiving fuel from a constant level vessel through a nozzle, a main air passage leading into said chamber, a vapor passage leading from the upper part of said chamber into the mixing conduit, the chamber having within it a wall enclosing an inner compartment into which the fuel nozzle directly delivers, and the chalnber having an upper extension with an air port leading into it, and

the inner compartment having an upper extenslon with an air mlet 1n almement with sald air port; whereby the a1r entering sald port tends to enter said inlet and increase the pressure within the compartment to assist the carburetion of fuel while the engine is being speeded up from idling condition. v

3. In a carburetor a-fucl chamber, a constant level vessel feeding into the chamber under restriction, a mixing passage having a zone of maximum suction, a channel conducting air and vapor from the chamber into the mixing passage near the maximum suction zone, a main air channel admitting atmospheric air to the chamber, and a supplemental air channel constantly conducting air from a point in advance of the maximum suction zone in the mixing passage to the chamber at a rate decreasing with increase of flow speed and suction in the mixing passage, whereby to control the suction in the chamber and thereby vary the fuel feed to preserve correct proportions of explosive mixture under variations of running conditions.

4. In a carburetor a fuel chamber, a constant level vessel feeding liquid fuel into the chamber under restriction, a mixing passage having a zone of maximum suction, a channel conducting air and vapor from the fuel chamber into the mixing passage near the maximum suction zone, a main air inlet admitting atmospheric air to the fuel chamber, and a supplementalair inlet comprising a channel constantly open located for conducting air from a point in advance of the maximum suction zone in the mixing passage to the fuel chamber at a rate varying in accordance with changes of flow speed and suction in the mixing passage, whereby to control the suction in the chamber and thereby vapor feed therefrom to the mixing passage.

In testimony whereof, this specification has been duly signed by GIACOMO MEMINI.

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